The day before, the large-scale liberation operation Cannonshot had commenced. In the middle of the night, Lieutenant Colonel Donald Alexander ("Don") Mackenzie and his men were loaded into Buffaloes at the Veerweg in Gorssel and ferried across the IJssel on April 12. Once on the western bank, Mackenzie directed his men northward towards Steenenkamer and De Hoven, while another company headed towards Wilp. The 30-year-old Mackenzie felt a tremendous responsibility for his men, especially when sending them into battle. In a conversation with his battalion intelligence officer, Lieutenant Jack Pickering, he expressed that this might be the last operation of his regiment.

After intense artillery fire from the Germans, the Canadians moved along both sides of the 2.5-meter-high dike towards the forest on the Wilpsedijk. A third group followed behind a Sherman tank, which moved slowly along the dike to keep pace with the leading platoons. The Germans were so focused on the tank that they were taken by surprise when the infantry stormed the forest at two o'clock in the afternoon and drove them out. At the same time, another company led by Major George Beal became bogged down just before an intersection near Twello. Beal crawled across flat terrain to reach the forward troops and relay the coordinates of German cannons to headquarters, as radio communications were generally poor. A surprise attack followed, and the Germans hastily retreated. Several Germans were killed, others abandoned their weapons, and fled for their lives.

Meanwhile, concerned about the lack of communication, Mackenzie decided to assess the situation himself and relocate his headquarters. Shortly before three o'clock, Mackenzie and Pickering set off in a jeep to find a new location east of Wilp. Along the way, they passed tanks under fire. Pickering wanted to remove Mackenzie from the firing, but Mackenzie asked Captain Bill Leadbeater to establish contact with his tanks.

While Mackenzie consulted the map next to the Sherman tanks to locate the companies, a grenade suddenly exploded next to them at exactly three o'clock. Pickering was critically wounded, and Mackenzie died within seconds from internal injuries. Mackenzie's death was a significant blow to the regiment amidst an ongoing attack. Major Counsell happened to be present at the tactical headquarters at that moment and was briefed by the injured Pickering about the status of the fighting. "It was a tremendous support. He refused to be evacuated to the Regimental Aid Post and insisted on staying with me until everything was under control," said Counsell. Nonetheless, they succeeded in liberating De Hoven and Steenenkamer.

Mackenzie was posthumously awarded the Distinguished Service Order (DSO) and the American Distinguished Service Cross (DSC).